This invention relates to a semiconductor light-emitting device and, more particularly, to a semiconductor light-emitting device capable of emitting blue to green light such as a semiconductor laser and a light emitting diode.
In recent years, there is a demand for semiconductor light-emitting devices, particularly, semiconductor lasers capable of emitting light with short wavelengths for improving recording densities of optical disks or resolutions of laser printers, and vigorous studies have been made for realization of such devices.
II-VI compound semiconductors are hopeful as materials to be used for fabricating such semiconductor light-emitting devices capable of emitting light with short wavelengths. In particular, ZnMgSSe compound semiconductors, which are quaternary II-VI compound semiconductors, are recognized to be suitable as materials of cladding layers and optical waveguide layers required to make on a GaAs substrate a semiconductor laser for emitting blue to green light in the band of wavelengths of 400.about.500 nm (see, for example, Electron. Lett. 28 (1992) 1798).
Such ZnMgSSe compound semiconductors, however, involve the problem that they are variable in lattice constant and in band gap energy due to changes in their compositions and make it difficult to stably fabricate semiconductor lasers.
There is also such a problem, particularly with p-type ZnMgSSe compound semiconductors used to make p-type cladding layers, that their effective impurity concentrations enabling doping are as low as 10.sup.17 cm.sup.-3, which causes high resistances of p-type cladding layers and hence causes generation of heat during operation of semiconductor lasers.